The present invention relates to an electronic component device and, more particularly, to an electronic component device, which has a side surface electrode or terminal portion in a recessed groove formed in a side surface or corner of a printed wiring board to extend from an upper surface to a lower surface, and on which a plurality of electronic component elements are mounted, and a method of manufacturing the same.
In general, as the device size decreases, not only components used by the device but also a printed wiring board on which the components are to be mounted must be downsized. Various improvements have been made to satisfy this requirement.
For example, as a method of mounting a plurality of electronic component elements, e.g., semiconductor elements or chip components, on a mother board, a method of temporarily mounting these plurality of electronic component elements on a printed wiring board (module board) and then mounting the printed wiring board on a mother board is available.
FIGS. 15 and 16 show a conventional printed wiring board manufacturing method and a state wherein a printed wiring board is mounted on a mother board, respectively.
Referring to FIG. 15, a two-sided metal laminated board 1 or so-called a large-sized board has a large outer shape. A large number of (nine in this example for the sake of convenience) printed wiring boards 2 are formed from the metal laminated board 1, and are mounted on a mother board 10, as shown in FIG. 16.
The conventional printed wiring board manufacturing method will briefly be described. A large number of through holes 4 are formed in the metal laminated board 1 by drilling along cutting lines 3 of the printed wiring boards 2 to be formed.
The metal laminated board 1 is plated, and is cut at the cutting lines 3, including the through holes 4, to form individual printed wiring boards 2 on the upper surface (if necessary, the lower surface as well) of the metal laminated board 1. On each printed wiring board 2, circuit conductors 5 and connection lands 6 are formed. The through holes 4 have been plated to form connection grooves 7 (by cutting along the through holes) at side surfaces, or corners adjacent to the side surfaces, of the resultant printed wiring boards, to extend from the upper surface to the lower surface, and to serve as plated side surface electrodes.
Electronic component elements 8 are attached to the connection lands 6 of each printed wiring board 2, formed in this manner, through solder 9. After that, solder 12 is heated to connect the side surface electrodes 7, formed in the side surfaces, or corners adjacent to the side surfaces, of the printed wiring boards 2, to lands 11 of the mother board 10, thereby mounting the printed wiring boards 2 on the mother board 10 such that they are connected to necessary portions on the mother board 10.
In each conventional printed wiring board 2 described above, since the connection grooves 7 serving as the side surface electrodes are hollow, as shown in FIG. 17, when the printed wiring board 2 is to be cut at the cutting lines 3 by press or router machining, a metal portion 7a to be cut may partly electrically deform and peel. The peeled metal portion 7a may form a metal burr 7b and enter the corresponding connection groove 7 which is to serve as a side surface electrode. The metal burr 7b may remain in the connection groove 7, as shown in FIG. 18. As a result, a plating conductor for forming the connection groove 7 of the side surface electrode tends to peel easily from the base material of the printed wiring board 2 due to the metal burr 7b. Then, the adhesion strength becomes short, and the conductor resistance of the connection groove 7 increases, thereby decreasing the reliability of electrical connection.
Since the connection grooves 7 to serve as the side surface electrodes are hollow, it is difficult to mount the electronic component elements 8 directly on the connection grooves 7. For this reason, in order to mount the electronic component elements 8 in other than the connection grooves 7, as shown in FIG. 19, lands 14 for mounting are formed independently of the lands of the connection grooves 7.
Accordingly, a distance L1 between the side surface of the printed wiring board 2 to the far end of the electronic component element 8 increases by a length AL of the corresponding land 14, and consequently the outer size of the printed wiring board 2 increases.
To allow each connection groove 7 to serve as the side surface electrode, a width C of the land (conductor) of the connection groove 7 cannot be decreased more than necessary, and a land diameter D1 of the connection groove 7 becomes larger than the connection hole diameter by twice (2C) the land diameter. Therefore, to decrease a pitch 11 among the connection grooves 7 is limited. As a result, downsizing of the printed wiring board 2 is interfered with.
As described above, since the conventional plated connection groove 7 which is to serve as the side surface electrode is hollow, when the electronic component element 8 is to be mounted in the connection groove 7 and encapsulated with a mold resin or the like, resin leakage occurs from the connection grooves 7, degrading the reliability.
It is, therefore, the principal object of the present invention to provide an electronic component device in which the connection reliability of a side surface terminal, formed in the side surface, or in a corner adjacent to the side surface, of a printed wiring board so as to continuously extend from the upper surface to the lower surface of the printed wiring board, is stabilized, and a method of manufacturing the same.
It is another object of the present invention to provide an electronic component device which can be downsized to be smaller than that of the prior art and which can enable high-density mounting of electronic component elements, and a method of manufacturing the same.
It is still another object of the present invention to provide an electronic component device which can be efficiently manufactured to improve productivity, and a method of manufacturing the same.
In order to achieve the above objects, according to an embodiment of the present invention, there is provided an electronic component device comprising a printed wiring board including a side surface terminal portion formed of a recessed groove formed in a side surface, or a corner adjacent to the side surface, of a board and extending from an upper surface to a lower surface, a filler which fills the groove and has a plating catalytic function, and a plating conductor covering an exposed surface of the filler.